1. Field
The embodiments discussed herein are directed to an optical transmission apparatus for controlling a variable optical attenuator, and a method for controlling the variable optical attenuator.
2. Description of the Related Art
Conventionally, wavelength division multiplexing (“WDM”) transmission has been viewed in terms of increasing transmission capacity. In the WDM transmission, an optical transmission apparatus controls a variable optical attenuator for variably attenuating received light and enlarges the dynamic range of intensity of receiving light.
In such an optical transmission apparatus, a variable optical attenuator is installed in a preceding stage of a light receiving module, and a change in the light receiving intensity is detected by a power monitor of the light receiving module, wherein feedback control is executed in accordance with a change in the corresponding light receiving intensity.
The light receiving module may be based on an MSA (multi-source agreement) by which product specifications may be standardized, and common specifications adopted for the purpose of compatibility among products from a plurality of vendors. Therefore, when a same type of apparatus is replaced, the optical transmission apparatuses may be produced by using light receiving modules from multiple vendors.
In using a light receiving module from multiple vendors, since characteristics of power monitors used to control a variable optical attenuator may differ from each other depending on the manufacturer and type, a problem exists in that design is difficult enabling the variable optical attenuator to execute appropriate operations by the same control circuit with respect to the light-receiving modules supplied from multiple vendors.